MORPHOLOGICAL CHARACTERISTICS OF ACELLULAR DERMAL MATRIX MANUFACTURING.

OBJECTIVE: The aim is to develop a method of the acellular dermal matrix manufacturing from pig's skin dermis while preserving the native structure. PATIENTS AND METHODS: Materials and methods: Combination of physical and chemical effects on the dermis underlies in the process of an acellular dermal matrix manufacturing. Dermal collection of 1.0-1.3 mm thickness in pigs under 1 year of age from the back and partially from the lateral parts of the body was carried out. The 0.3-0.4 mm thickness layer of skin was previously removed from the relevant areas with help of a dermatome, which was physically and chemically treated. The maximum acellularization of the dermal matrix was achieved step-by-step and included four stages of skin processing: 1 - freeze-thaw process; 2 - glycerin dehydration; 3 - osmotic stress; 4 - cell residue removal by detergent. RESULTS: Results: Histological analysis of the of the pig's skin dermis revealed that after freeze-thaw cycles the collagen scaffold of the dermal matrix maintains its structural organization that was obtained as a result of the first stage of decellularization. On the second stage of decullalarization, the decreased number of fibroblastic cells was indicated. By means of this, the connective tissue elements that are represented by collagen fibers' multidirectional bundles retained their structural organization. Fibroblasts lysis as basophilic stained elements was revealed in small amount of dermis on the third stage of the decellularization. Washing of lyophilized skin with nonionic detergent sodium dodecyl sulfate the complete absence of fibroblasts, epidermocytes in the hair follicles, endothelial cells in the wall of blood vessels was detected indicating the effectiveness of this reagent in removing residual products. CONCLUSION: Conclusions: Suggested protocol for decullalarization of the pig's skin dermis is effective in removing nuclear and cellular structures from dermis. Particular protocols can be modified by increasing the temperature difference or changing the number of freeze-thaw cycles.

COVID-19-associated acute respiratory distress syndrome versus classical acute respiratory distress syndrome (a narrative review).

Coronavirus disease 2019 (COVID-19), caused by the novel coronavirus, Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2), led to the ongoing global public health crisis. Existing clinical data suggest that COVID-19 patients with acute respiratory distress syndrome (ARDS) have worse outcomes and increased risk of intensive care unit (ICU) admission. The rapid increase in the numbers of patients requiring ICU care may imply a sudden and major challenge for affected health care systems. In this narrative review, we aim to summarize current knowledge of pathophysiology, clinical and morphological characteristics of COVID-19-associated ARDS and ARDS caused by other factors (classical ARDS) as defined by Berlin criteria, and therefore to elucidate the differences, which can affect clinical management of COVID-19-associated ARDS. Fully understanding the characteristics of COVID-19-associated ARDS will help identify its early progression and tailor the treatment, leading to improved prognosis in severe cases and reduced mortality. The notable mechanisms of COVID-19-associated ARDS include severe pulmonary infiltration/edema and inflammation, leading to impaired alveolar homeostasis, alteration of pulmonary physiology resulting in pulmonary fibrosis, endothelial inflammation and vascular thrombosis. Despite some distinct differences between COVID-19-associated ARDS and classical ARDS as defined by Berlin criteria, general treatment principles, such as lung-protective ventilation and rehabilitation concepts should be applied whenever possible. At the same time, ventilatory settings for COVID-19-associated ARDS require to be adapted in individual cases, depending on respiratory mechanics, recruitability and presentation timing.

Morphogenesis of maxillary sinuses in infants, during early and first childhood.

OBJECTIVE: The aim: To study the peculiarities of the structure and to see the development of maxillary sinuses in infants, during the early and first childhood periods of human ontogenesis. PATIENTS AND METHODS: Materials and methods: The study of the peculiarities of the development and formation of the maxillary sinuses' wall was carried out on 50 species of the upper jaws, turtles and sections of the head of the human corpses during different periods of ontogenesis (in infants, during early and first childhood) with the help of histological examination, preparation, CT scan, radiography and morphometry. RESULTS: Results and conclussions: In infants and during the early and first childhood periods of human ontogenesis in the MS there are changes in both quantitative and qualitative nature. In infants (10 days - 1 year), maxillary sinuse is located more lateral to the basis of the lower nasal concha. In this period, it begins to form its lower wall, which in the form of a narrow strip invaginates into the alveolar process. The growth of the sinus is due to the protrusion of the external wall in the direction of the zygomatic bone. The wall of the maxillary sinuse is covered with mucosa (respiratory mucous membrane), which is lined by pseudostratified columnar ciliated epithelium, which is located on the basement membrane. X-ray examination of maxillary sinuse in infants shows that it is a pear-shaped in the anterior projection. Clearly the following walls of the sinuses are visible: the upper, the lower, one, which is arched-shaped, the front and the median, which in lower part are crossed as arch to each other. Investigation of biological specimens of the maxillofacial area of the early childhood period (1-3 years) showed that maxillary sinuses in all specimens are determined more laterally to the basis of the lower nasal concha. Its vertical dimension is 7.5-8.0 mm, transverse - 5.7-6.0 mm, anterior-posterior - 13.9-14.5 mm. X-ray examination of maxillary sinuse in early childhood in the front projection shows that it has an oval shape. There are the following walls of the sinus: upper, lower, front and middle. The study of biological specimens of the facial area in the period of the first childhood (4-7 years) has been established that the configuration of maxillary sinuse is changing. All walls are determined, but the upper wall is rather short, and the front wall is narrow. The median wall has the most prominent development. On X-rays in the anterior projection, a slight extension of the maxillary sinuse is noted laterally. Therefore, one should thoroughly study the peculiarities of the development and structure of the walls of the maxillary sinuses in order to prevent the development of complications and to achieve the treatment of inflammatory diseases of the MS in an optimal term.